you are correct. In a constant bank LEVEL turn, load factor is increased. when load factor is increased, stall speed is increased proportional to the square root of the load factor. When in a descending turn you are taking some of that loading off the wing. remember, lift is OPPOSING gravity(weight,load). Think about it as letting gravity do its work by making your airplane go towards the ground, whereas if you stayed level the wings would actually have to work harder against gravity to keep you there...load factor.